The objective of this research is a better understanding of the structure and dynamics of phospholipid bilayer membranes including their thermal phase separation behavior. An auxilliary objective is the continued development of new techniques for the study of membranes. The major techniques to be used in these studies involve the fluorescence or absorption properties of the 18-carbon tetraene parinaric acid and s curve of its derivatives. Phospholipid phase diagrams, the properties of asymmetric lipid bilayers, the dynamics of the acyl chains in bilayers and the rate of lateral diffusion of lipids in bilayers will be determined using calorimetric methods and several fluorescence measurements including fluorescence polarization, lifetime, nanosecond decay and energy transfer. The extension of these techniques to studies of lipid protein interactions is also proposed.